1. Field of the Invention
This invention relates to a method for treating pipelines, flow lines, and other equipment used in the production of oil and gas with chemicals useful for reducing corrosion, scale, asphaltenes and other undesirable conditions. This invention particularly relates to a method for the controlled placement of such chemicals and the controlled release of these chemicals.
2. Background of the Art
Fluids produced from oil wells penetrating an oil-bearing formation primarily include crude oil and water and are herein referred to as system fluids. A system fluid may also contain natural gas which may or may not be desirable and may be the primary product of a given well in which case the well is referred to as a gas well. A system fluid may also contain CO2 and will often contain oil and water insoluble compounds such as clay, silica, waxes, and asphaltenes, which exist as colloidal suspensions. In addition to the already listed components, system fluids can also include inorganic components that can precipitate to form mineral scales. These materials may be undesirable in the exploration for and production of oil and gas.
It is known in the art of oil and gas production to eliminate or mitigate the effects these undesirable materials. For example, during oil and gas production in production wells, the drilling of new wells, or workovers of existing wells, many chemicals, referred herein as “additives;” which include scale inhibitors, paraffin inhibitors, corrosion inhibitors and the like; are often injected from a surface source into the wells to treat the system fluids flowing through such wells to prevent or control the precipitation of mineral scale and/or paraffins, and to protect the well against corrosion. These additives can be injected continuously or by batches through a conduit or tubing that is run from the surface to a known depth within the formation, typically upstream of the problem location.
In addition, an additive can be injected into a near wellbore formation via a technique commonly referred to as “squeeze” treatment, from which the additive can be slowly released into the system fluid. Sometimes, additives are introduced in connection with electrical submersible pumps, or through an auxiliary line associated with a cable used with the electrical submersible pump. In addition, in wells without a packer, additives may be applied via pump or truck into the annular space between the tubing and the casing with a fluid flush driving the additive into the system fluids.
In most of these operations, the additives are in the form of aqueous-eternal micro-emulsions or admixtures, although organic solutions are also known. The use of liquid additives is not without problems. In cold weather, the additives may freeze or gel during transportation or use. Supplying a source of heat, particularly for remote well sites can be a problem.
One issue that sometimes arises in treating oil and gas exploration and production equipment is in getting the additives to the location where they are most needed. It does not do any good to treat formation fluid in an oil well to, for example, prevent corrosion, if the corrosion that was a problem actually was occurring in locations upstream from the oil well. It would be particularly desirable in the art of treating oil and gas production equipment with additives to locate the additives at the point within the oil and gas production equipment that requires the treatment for which the additives are used.